1. Field of the Invention
This invention relates to nutritive compositions containing fatty substances, and to a process for the preparation of said compositions from fruits of the Ribes genus.
2. Description of Related Art
Most vegetable oils contain linolenic (6,9-octadecadienic) and .alpha.-linolenic (9,12,15-octadecatrienic) polyunsaturated fatty acids. Only oils of the seeds of hops (Humulus), of hemp (Cannabis), of borage (Borage) and of evening primrose (Oenothera) are known as containing .gamma.-linolenic (6,9,12-octadecatrienic) acid, evening primrose being the only available source at, moreover, a high price.
.gamma.-Linolenic acid is an essential fatty acid which is metabolised by the organism into prostaglandins via dihomo-.gamma.-linolenic acid and arachidonic acid (5,8,11,14-eicosatetraenic), which is itself a constituent of cellular membranes, whereas .alpha.-linolenic acid does not take part in the same way in this metabolic process. The linoleic acid conversion into .gamma.-linolenic acid in the tissue is incomplete (4-20% compared to 90-98% for the conversion of .gamma.-linolenic acid into arachidonic acid) and may not even exist (for example in cats) in the case of the absence or the inactivation of the enzyme .DELTA.-6-desaturase.
In effect, a lack of essential fatty acids results in a nutritional deficiency affecting all the metabolic processes which have been mentioned above and which may result in biochemical disorders or in organic lesions (for example coagulation disorders, dermatological lesions, endocrinal complaints, myocardiac lesions, and hepatic, articular, neurological and mental disorders). Therefore, it is possible to see the advantages provided by a supply of .gamma.-linolenic acid for the prevention or for the treatment of these anomalies.
The possibility of using .gamma.-linolenic acid and arachidonic acid as therapeutic and nutritional agents has been mentioned in, for example French Patents Nos. 2,197,605 and 1,603,383, .gamma.-linolenic acid being of a synthetic origin or being extracted from the oil of evening primrose (Oenothera) or officinal borage (Borage officinalis) seeds.
Moreover, French Patent No. 2,255,055 relates to cosmetic or pharmaceutical compositions based on the oil of raspberry pips, the anti-inflammatory activity of which is mentioned, but with no indication of the composition. Since the oil is preferably extracted using chloroform (a polar solvent), the anti-inflammatory activity is probably due to the presence of minor components. Moreover, analysis of this oil has shown that it contained about 54% by weight of linoleic acid and 30% of a .alpha.-linolenic acid, but did not contain any .gamma.-linolenic acid.
Finally, Hungarian Patent No. T 13226 states that the addition of a pulp or a crude oil extracted from paprika, tomato or redcurrant pips to cosmetic products or table oils would inhibit their oxidation. The extraction, as it is described, does not allow the separation of the undesirable waxes and colourings in the products which are envisaged and the composition of the extract is not mentioned.